Tags: Star.
21 Arietis is the Flamsteed designation for a binary star system in the northern constellation of Aries. It has a combined apparent visual magnitude is 5.57; the brighter member is magnitude 6.40 while the fainter star is magnitude 6.48. The distance to this star system based upon an annual parallax shift of 19.58 mas is 167 light-years (51 parsecs). The pair orbit each other with a period of 23.70 years and an eccentricity of 0.68.